Problem: Simplify the following expression: $t = \dfrac{4r - 9}{7} \div \dfrac{7r}{10}$
Explanation: Dividing by an expression is the same as multiplying by its inverse. $t = \dfrac{4r - 9}{7} \times \dfrac{10}{7r}$ When multiplying fractions, we multiply the numerators and the denominators. $t = \dfrac{ (4r - 9) \times 10 } { 7 \times 7r}$ $t = \dfrac{40r - 90}{49r}$